1. Field of the Invention
The present invention relates to an antenna structure, and especially relates to an antenna structure for using with a metal frame of a mobile phone.
2. Description of the Related Art
The mobile phone is rigid and stylish because of the metal frame. Therefore, the metal frames are used widely for the mobile phones. However, the metal frame effects the radiation of the mobile phone very much. The related art antenna structure of the mobile phone is difficult to avoid the influence of the metal frame.
In order to avoid the influence of the metal frame, the area (near the antenna structure) of the metal frame of the mobile phone will be removed or reduced (replaced by the plastics). Or the metal frame is divided into several parts, and then some parts of the metal frame are used as the antenna structure. Besides, the planar slot antenna with micro strip line feeding is used to avoid the influence of the metal frame as well (as shown in China patent application number CN201120421743.8).
The methods mentioned above have following disadvantages.
1. The mobile phone is not stylish and the volume of the antenna structure is larger if the metal parts near the antenna structure are replaced by the plastics.
2. There are slots between some parts of the metal frame which are used as the antenna structure. The performance of the antenna structure is bad (or changed) if user's hand (or other conductors) holds (or touches) the slots.
3. There are slots on the circuit board if the planar slot antenna with micro strip line feeding is applied. Therefore, large area of the circuit board will be occupied and be used by the slots.